Optical fiber adapter

ABSTRACT

An adapter for mating optical fiber connectors may include an internal configuration that essentially holds the ferrules of the connectors in alignment when a force is applied to the connector in a sideways direction. An internal plate may be provided to essentially prevent displacement of the mating ends of the ferrules with respect to the adapter housing and one another.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/741,268, filed Jun. 16, 2015, which claims the benefit of U.S.Provisional Application No. 62/013,216 filed on Jun. 17, 2014, thecontents of both of which are incorporated by reference in theirentirety as if fully set forth herein.

BACKGROUND

Demand for bandwidth by enterprises and individual consumers continuesto experience exponential growth. To meet this demand efficiently andeconomically, data centers have to achieve ultra-high density cablingwith low loss budgets. Fiber optics have become the standard cablingmedium used by data centers to meet the growing needs for data volumeand transmission speeds.

Individual optical fibers are extremely small. For example, even withprotective coatings, optical fibers may be only about 250 microns indiameter (only about 4 times the diameter of a human hair). As such,hundreds of fibers can be installed in cables that will take uprelatively little space. For connections between cables, however, thefibers are terminated with connectors. Multiple fibers may be arrangedwithin a single connector. For example, multi-fiber connectors such asthose using multi-fiber push-on/pull-off (MPO) technology may containand connect 12 or 24 fibers. Connectors, such as MPO type connectors,generally include a housing portion that contains a ferrule thatterminates the ends of the fibers. Ferrules are generally used to retainthe ends of the optical fibers for connecting the optical fibers. Onetype of optical ferrule that may be used with MPO type connectors is anMT (Mechanically Transferable) ferrule.

Typically, MPO connectors are joined together to connect the opticaltransmission path of one fiber optic cable to another fiber optic cableor device, and the connection may be made by inserting the MPOconnectors in an MPO adapter. An adapter generally includes a housing,or portion of a housing, having at least one port which is configured toreceive and hold a connector to facilitate the optical connection of theconnector ferrule with the ferrule of another connector or other device.Adapters may be used to facilitate connections contained within achassis. The term “chassis” as used herein broadly refers to acontainment structure for housing electrical components or switchingcomponents.

Ferrules, disposed within the connector housings, get pushed togetherwithin the adapter to optically connect the ferrules by means of aso-called PC (Physical Contact) connection, wherein the optical fibersin one ferrule contact the optical fibers in the other ferrule and getcompressed together to provide an optical connection. Opticaltransmission performance between the optical fibers is stronglydependent on connecting conditions such as axis alignment andinclination of the optical fibers, and gaps between the opposing opticalfibers.

Any slight misalignment or incorrect inclination of ferrules may degradethe quality of the signal being transmitted. In a chassis-type system,for example, wherein the adapter is mounted to a surface, a plugged-inconnector of the adapter may be accidentally bumped or displaced,thereby causing movement of the ferrule of the displaced connectorrelative to the adapter and/or the ferrule of another connector mountedthereto.

Such a sideways force, or side-loading, on an MPO connector that ismated with another MPO connector generally results in an increase inInsertion Loss (attenuation) of the power as the signal being carriedexits one MPO connector and enters the mated MPO connector. Side loadingmay result in a microscopic separation between the contacting surfacesof mated MPO ferrules, and such a separation creates an air gap betweenthe otherwise contacting end surfaces of the mated ferrules. Any amountof air present between the contacting surfaces of optical connectors mayact as a restriction to the light wave passage and, although not a totalloss in transmission, may result in fractional power loss. It isdesirable to eliminate any power losses present in any fiber opticnetwork.

Therefore, in order to reduce or eliminate potential power loss withinan adapter, there remains a need for minimizing movement of connectorferrules after installation in an adapter.

SUMMARY

To prevent, or at least minimize, movement of ferrules within an adapterafter the optical fiber connectors are plugged into the adapter, anadapter may be provided with an internal configuration that essentiallyholds the ferrules in alignment. Thus, when a force is applied to aconnector in a sideways direction (a force that has a component that isnot parallel to the installation or plug-in direction), movement of theprotruding contact end of the corresponding ferrule within the adapterand/or with respect to the opposing ferrule in the adapter, may at leastbe minimized, if not completely prevented. In an embodiment, the adaptermay be an MPO optical fiber adapter, the connectors may be MPO opticalfiber connectors, and the ferrules may be MT ferrules.

In an embodiment an optical fiber adapter is provided for opticallycoupling two optical fiber connectors, wherein each optical fiberconnector has an optical ferrule with a mating end for mating with themating end of the optical ferrule of the other connector. The adapterincludes a housing having a first end, a second end opposite the firstend, and defines an axial cavity extending from the first end to thesecond end, and each of the first end and the second end beingconfigured for receiving and selectively retaining one of the opticalfiber connectors therein for mating of the mating ends of the opticalferrules at a mating location within the housing. The housing includes awall portion disposed at the mating location and orthogonal to the axialcavity, and the wall portion includes an opening therein for the axialcavity and a perimetrical surface defining the opening, wherein theopening has a cross-sectional configuration for unhindered passage ofthe mating ends of the optical ferrules therethrough, and the wallportion, at least adjacent the opening, has a wall thickness sufficientfor engagement of the mating ends of the optical ferrules with theperimetrical opening upon displacement of the mating ends in anydirection orthogonal to the axial direction to limit lateral movement ofthe mating ends and substantially maintain an optical coupling betweenthe mating ends.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B depict perspective views of an MPO adapter according toan embodiment.

FIG. 2 depicts a partially disassembled view of an MPO adapter withadapter cover removed according to an embodiment.

FIGS. 3A-3C depict various views of an MPO adapter housing according toan embodiment.

FIGS. 4A and 4B depict various views of an MPO adapter clip according toan embodiment.

FIGS. 5A-5D depict various views of an adapter cover with insertaccording to an embodiment.

FIGS. 6A-6D depict components of an MPO adapter and relativefitting-together of the components according to an embodiment.

FIGS. 7A and 7B provide cross-sectional views of an assembled MPOadapter along line VII-VII of FIG. 1 according to an embodiment.

FIGS. 8A and 8B provide cross-sectional representations of an MPOadapter with a representative MPO connector and MT ferrule installedaccording to an embodiment.

FIGS. 9A and 9B depict the internal configuration of an adapter forlimitation of ferrule movement within the adapter according to anembodiment.

DETAILED DESCRIPTION

While the following description is directed towards MPO adapters and MPOconnectors with MT optical ferrules, the embodiments described may beapplicable to other adapters, connectors and ferrule types as well. Asrepresented in the embodiments of FIGS. 1A and 1B, an MPO adapter 10 mayinclude a first end 12 having a first plug-in port 14 for receiving anMPO optical fiber connector therein, and may include a second end 16having an additional plug-in port 18 for receiving an additional MPOoptical fiber connector therein.

For retention of an MPO connector within each of the ports 14, 18, theports may be provided internally with a connector clip 20. The clips 20(shown in isolated views in FIGS. 4A and 4B) may include resilient tabs22 a and 22 b configured to be displaceable outwardly for insertion andremoval of a connector into or out of the ports 14, 18, and return toessentially their original position to engage and retain a connector inthe ports. For adapters 10 configured to be mounted on a chassis panel,mounting flanges 24 a, 24 b may be provided on the adapter to mount theadapter via screws, for example, or alternatively, a panel mounting clip26 may be provided on one end of the adapter.

As shown in additional detail in FIG. 2, an adapter 10 may include ahousing 30 and a housing cover 32. The housing 30 (shown in isolatedviews in FIGS. 3A-3C) may include a corresponding opening 34 configuredfor receipt of the cover 32 therein as shown in FIG. 1A. The connectorclips 20 may be installed in the housing 30 via the opening 34. Eachclip 20 may be independently inserted into the housing 30 through theopening 34 and then slid and fit into position as shown. The housingcover 32 may be installed to enclose the clips 20 within the housing 30.In an embodiment, the housing cover 32 may be ultrasonically welded tothe housing 30. Alternatively, as represented in the drawings, thehousing cover 32 may include a plurality of engagement projections 36that frictionally engage within corresponding receptacles 38 of thehousing 30. In an embodiment as depicted, the housing 30 and housingcover 32 may include six such projections 36 and correspondingreceptacles 38. Various alternate embodiments of the housing cover 32and the housing 30 as well as the method of attaching the cover to thehousing may be provided, for example, by adhesive.

In an embodiment, and as described in more detail herebelow, the cover32 may include a housing wall portion 40 and an insert plate 42 thatextends substantially orthogonally to wall portion to fit between theclips 20 in the insert gap 44. Upon insertion of the plate 42 into thegap 44 the clips 20 may be retained in place within the housing 30.

FIGS. 3A and 3B provide isolated perspective views of the housing 30,and FIG. 3C provides an overhead view looking down into the housing 30through the opening 34. In an embodiment as shown in FIGS. 3A and 3B,the housing 30 may include side-wall and bottom depressions 50 a, 50 bconfigured for receiving the panel mounting clip 26 therein so that theclip is maintained in place on the housing. In addition, internallywithin the housing 30, stops 52 may be provided to retain the clips 20within the housing and prohibit the clips from being pushed or pulledthrough the ends 12, 16. The interior of the housing 30 may also includealignment features, such as notches 54, for mating with projections 56of the clips 20 (see FIGS. 4A, 4B) to ensure that the clips are properlyinstalled within the housing.

As shown in FIGS. 4A and 4B, a clip 20 may include a base 58 and wallportions 60 a, 60 b that extend substantially orthogonally from thebase. Resilient tabs 22 a, 22 b may also extend substantiallyorthogonally from the base 58 so that the tabs and wall portions 60 a,60 b define a central internal cavity 62 for receiving an optical fiberconnector therein. The protruding ends of resilient tabs 22 a, 22 b maybe provided with catches 64 a, 64 b for engaging with a connector toretain the connector within the opening once inserted therein.

FIGS. 5A-5D provide various additional views of the housing cover 32. Asmentioned previously, and as also represented in FIGS. 6A-6D, housingcover 32 includes an insertion plate 42 that is configured to fitbetween the two clips 20 when inserted into the housing 30. Theinsertion plate 42 may have a thickness t₁ (FIG. 5B) that matches thewidth of the insert gap 44 (FIGS. 6A and 6C) that exists between clips20 after positioning of the clips within the housing 30.

FIG. 6A provides a perspective view of two clips 20 positioned inrelation to one another as they may be positioned within a housing, asalso shown in a side view in FIG. 6C with the overlay outline of ahousing 30. FIGS. 6A and 6C also provide a representation of a housingcover 32 in general relative positioning for insertion of the plate 42between the clips 20. FIG. 6B provide an assembled views of the housingcover 32 and two clips 20 positioned in relation to one another as theymay be positioned within a housing, as also shown in a side view in FIG.6D with the overlay outline of a housing 30.

As shown in FIGS. 5A and 5C, insertion plate 42 may include an innerwall portion 42 a that may be of a thickness t₂ (see FIG. 7B) that isless than the thickness t₁ and which includes an inner opening 43provided for allowing contact between mating ferrules within the housingas discussed further below.

FIG. 7A provides a cross-sectional view of an assembled adapter 10 takenalong line VII-VII of FIG. 1A, and FIG. 7B shows an enlarged detail ofthe rectangular section marked in FIG. 7A. As shown in FIG. 7B, theinternal wall portion 42 a of the insertion plate 42 may have athickness t₂ that is less than the thickness t₁ of the plate 42. In anembodiment, the internal wall portion 42 a may have a thickness t₂ thatis sufficient to provide a perimetrical surface around the opening 43that may be of a size sufficient to engage with and at least minimizelateral movement of a ferrule disposed within the adapter.

FIG. 8A provides a cross-sectional view of an assembled adapter 10having one optical fiber connector 70 inserted within a port 14 of theadapter. As shown, a connector 70 may include a connector housing 72that fits within a clip 20. The connector housing 72 may includeprojections 74 a, 74 b that engage within the catches 64 a, 64 b of theclip 20 to retain the connector within the adapter 10. In the insertedposition, a leading end 72 a of the connector housing 72 may approach,and in an embodiment as shown, contact the internal wall portion 42 a ofthe insertion plate 42.

In an embodiment as represented in FIG. 8A, the leading end 72 a of theconnector housing 72 may pass over the joint 80 (shown in more detail inFIG. 7B) that forms between the insertion plate 42 and adjoining clip20. Since slight inaccuracies in molded parts may occur when the partsare being formed, and/or misalignments may occur during assembly, itwould be undesirable for the internal profile 82 of the insertion plate42 to protrude into the path of the connector housing, as this may causea problem with insertion of the housing into the adapter, and/ormisalignment of the ferrules. To avoid this type of problem, theinternal profile 82 of the insertion plate may be larger than theinternal profile 84 within a clip 20 by an amount d₁, therebyessentially removing the possibility that the profile of the insertionplate may protrude into the path of the connector housing.

The connector 70 may include a ferrule 76 within the connector housing72, and the ferrule may be biased outwardly away from the connector (bya biasing member, not shown) so that a mating end 78 of the ferruleprotrudes from the connector 70 as shown in FIG. 8A. Opening 43 withinthe internal wall portion 42 a of the insertion plate 42 may be sized toallow uninhibited passage of the ferrule end 78 therethrough. In anembodiment, without the presence of a second connector within theadapter 10, as shown in FIG. 8A, the mating end 78 of the ferrule 76 mayextend completely through the opening 43. In an embodiment, it would beundesirable for the ferrule end 78 to engage the internal wall portion42 a upon insertion of a connector 70 into an adapter 10 to avoidimproper mating of ferrules within the adapter. Since a degree ofmisalignment and/or play may occur during insertion of a connector 70into an adapter 10, in an embodiment, the dimensions of the opening 43may be larger than the dimensions of the ferrule end 78 by about 0.2 mmto about 0.6 mm.

In an embodiment, an MT ferrule, for example, may have dimensions ofabout 6.4±0.1 mm×2.5±0.1 mm. A corresponding opening 43 may have a widthof about 6.7 mm to about 6.9 mm and a height of about 2.8 mm to about3.0 mm. In general, an opening 43 may be larger than the ferrule end 78by a factor of at least about 1.03 (6.7 mm/6.5 mm) and at most about1.25 (3.0 mm/2.4 mm). In various embodiments for an MPO connector of thedimensions indicated, the width of the opening may be about 6.7 mm,about 6.72 mm, about 6.74 mm, about 6.76, about 6.78 mm, about 6.80 mm,about 6.82 mm, about 6.84, about 6.86 mm, about 6.88 mm, or about 6.9mm, or any value between any of the listed values, and the height may beabout 2.80 mm, about 2.82 mm, about 2.84, about 2.86 mm, about 2.88 mm,about 2.90 mm, about 2.92 mm, about 2.94, about 2.96 mm, about 2.98 mm,or about 3 mm, or any value between any of the listed values.

For embodiments, the minimum dimensions of the opening may be configuredin conjunction with the maximum dimensions of the ferrule so thatinsertion of the ferrule into the opening is not obstructed by the walldefining the opening. In addition, the maximum dimensions of the openingmay be configured in conjunction with the minimum dimensions of theferrule so that any movement of the ferrule within the opening willresult in contact of the ferrule with the wall in a manner as discussedbelow.

In an embodiment, as represented in FIG. 8B, upon insertion of a secondconnector 70 into the opposing end of the adapter 10, the biasing forcesof the opposing ferrules 76-1 and 76-2 may essentially be equalized asthe mating ends 78-1 and 78-2 mate with one another. With essentiallyequal biasing force, the mating ends 78-1 and 78-2 should mate with oneanother at essentially the center of the wall portion 42 a (shown in thefeatured circle in the lower right of FIG. 8B).

The mated ferrules 76-1, 76-2 within the adapter 10 provide a PhysicalContact (PC) connection, wherein the optical fibers in one ferrulecontact the optical fibers in the other ferrule and get compressedtogether to provide an optical connection. With this type of connection,optical transmission performance between the optical fibers is stronglydependent on connecting conditions such as axis alignment andinclination of the optical fibers, and gaps between the opposing opticalfibers.

If a plugged-in connector 72-1, 72-2 were to be accidentally bumped ordisplaced, thereby causing movement of the corresponding ferrule 76-1,76-2 an increase in Insertion Loss (attenuation) of the power of thesignal being carried by the optical fibers may occur as a microscopicseparation between the contacting surfaces of mated ferrules may result.In order to hold the corresponding ferrules 76-1, 76-2 of the twoconnectors 72-1, 72-2 in good alignment within the coupling adapter 10,additional internal structure of the wall insert 42 provided by newstructural surfaces 81-1, 81-2 (shown in FIG. 9B and defined by thethickness of the wall portion 42 a), may be provided to negate theeffects of side loads placed onto one or both of the connectors.

In an embodiment as represented in FIGS. 9A and 9B, to minimize orpossibly eliminate such an increase in insertion loss caused by anyside-load displacement, the wall portion 42 a of the insertion plate 42may be configured with a thickness t₂ (FIG. 7B) that is sufficient tominimize or block any lateral movements of a ferrule 76-1, 76-2 withinthe adapter 10. FIG. 9A depicts a side, cross-sectional view of anassembled adapter 10 and FIG. 9B shows an enlarged detail of the matingferrule ends 78-1, 78-2.

In the represented embodiment in FIGS. 9A and 9B, a downward force F isapplied to ferrule 76-1, displacing the ferrule from its originalposition p₁ causing the mating end 78-1 to move upwardly as representedby m and into a new position p₂. This movement is limited however by thewall portion 42 a when the upper surface of ferrule end 78-1 contactsthe surface 81-1. In the absence of the wall portion 42 a, or if thewall portion 42 a is not of a thickness t₂ sufficient to block thisupward movement m, the mating ends 78-1 and 78-2 may become sufficientlydisplaced from one another to cause a decrease in signal quality beingtransferred between the ferrule 76-1, 76-2.

In an embodiment for an adapter for MPO connectors as shown, thethickness t₂ may be about 0.6 mm±0.1 mm. In embodiments, for example,the thickness t₂ may be about 0.5 mm, about 0.52 mm, about 0.54 mm,about 0.56 mm, about 0.58 mm, about 0.60 mm, about 0.62 mm, about 0.64mm, about 0.66 mm, about 0.68 mm, or about 0.7 mm, or any value betweenany of the listed values.

In an embodiment, thickness t₂ may extend up to essentially thethickness t₁ of the wall insert 42, or alternatively, the thickness t₁of the wall insert 42 may be minimized to be essentially only thethickness t₂ that is needed to minimize any movement m.

While the embodiment as shown and described may relate to a downwardside load F (in relation to the orientation of the depiction shown onthe drawing page) with an upward displacement m of the ferrule end 78,the same description and functioning may also be applied to any otherside loads F (upwardly, or into or out of the page relative to thedepiction as shown). In other words, any movement m may also beminimized or blocked in the opposite downward direction if the side loadF were to be applied in an upward direction. In addition, any movement minto and out of the page of the figure may also be minimized or blockedif the side load F were to be applied in a sideways direction (also intoor out of the page of the figure).

In an embodiment, the dimensions of the opening 43 (as discussed indetail above) may be configured in conjunction with the thickness t₂todetermine the amount of movement m, so that any movement m may beminimized, if not completely blocked. For example, the thickness t₂ maybe less if the opening 43 is smaller and more closely matches thedimensions of the ferrule end providing a narrow gap between the surface81-1 and the ferrule end 78-1, and alternatively, the thickness t₂ mayneed to be larger if the opening 43 is larger and defines a larger gapbetween the surface 81-1 and the ferrule end 78-1. By providing aconfiguration that minimizes or blocks movement of the ferrule endswithin the adapter, the optical performance of the connection may beimproved by countering side loads that may be exerted to one or both ofthe mated connectors.

In an embodiment, a reduced thickness t₁ of the wall insert 42, mayallow for the thickness t₃ of the base 58 of a clip 20 to be increased(FIG. 4A). In an embodiment having short clips, for example, that mayallow for easier insertion and assembly, the thickness t₁ may be about5.2 mm, and the thickness t₃ of the base 58 of each clip 20 may be about0.8 mm (Total t₁+t₃+t₃=about 6.8 mm). Such a relatively thin base 58however, may allow for easier deformation under a side load that may beapplied to the adapters 10 as discussed above, possibly resulting in abending/bowing of the base that may, under sufficient load, allow for atleast one of the arms 22 a and 22 b to be outwardly displaced away fromthe other arm, allowing the clip 20 to open, releasing a connector heldtherein. By increasing the thickness t₃ of the base 58, the base may bemore resistive to bending/bowing, and thus less likely to open underloads. In an embodiment, the thickness t₁ may be decreased to about 2mm, and the thickness t₃ of the base 58 of each clip 20 may be increasedto about 2.4 mm (Total t₁+t₃+t₃=about 6.8 mm).

In an embodiment, the base thickness t₃ may be about 1.70 mm to about1.80 mm. In various embodiments, for example, the base may have athickness of about 1.70 mm, about 1.72 mm, about 1.74 mm, about 1.76 mm,about 1.78 mm, about 1.8 mm, or a value between any of the listedvalues.

This disclosure is not limited to the particular systems, devices andmethods described, as these may vary. The terminology used in thedescription is for the purpose of describing the particular versions orembodiments only, and is not intended to limit the scope.

In the above detailed description, reference is made to the accompanyingdrawings, which form a part hereof. In the drawings, similar symbolstypically identify similar components, unless context dictatesotherwise. The illustrative embodiments described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherembodiments may be used, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope, as will be apparentto those skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, reagents, compounds, compositions or biological systems, whichcan, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular embodimentsonly, and is not intended to be limiting.

As used in this document, the singular forms “a,” “an,” and “the”include plural references unless the context clearly dictates otherwise.Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art. Nothing in this disclosure is to be construed as anadmission that the embodiments described in this disclosure are notentitled to antedate such disclosure by virtue of prior invention. Asused in this document, the term “comprising” means “including, but notlimited to.”

While various compositions, methods, and devices are described in termsof “comprising” various components or steps (interpreted as meaning“including, but not limited to”), the compositions, methods, and devicescan also “consist essentially of” or “consist of” the various componentsand steps, and such terminology should be interpreted as definingessentially closed-member groups.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations). Furthermore, in thoseinstances where a convention analogous to “at least one of A, B, and C,etc.” is used, in general such a construction is intended in the senseone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, and C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). In those instances where a convention analogous to “atleast one of A, B, or C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, or C” wouldinclude but not be limited to systems that have A alone, B alone, Calone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). It will be further understood by those withinthe art that virtually any disjunctive word and/or phrase presenting twoor more alternative terms, whether in the description, claims, ordrawings, should be understood to contemplate the possibilities ofincluding one of the terms, either of the terms, or both terms. Forexample, the phrase “A or B” will be understood to include thepossibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” and the like include the number recited andrefer to ranges which can be subsequently broken down into subranges asdiscussed above. Finally, as will be understood by one skilled in theart, a range includes each individual member. Thus, for example, a grouphaving 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, agroup having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells,and so forth.

Various of the above-disclosed and other features and functions, oralternatives thereof, may be combined into many other different systemsor applications. Various presently unforeseen or unanticipatedalternatives, modifications, variations or improvements therein may besubsequently made by those skilled in the art, each of which is alsointended to be encompassed by the disclosed embodiments.

What is claimed is:
 1. An optical fiber adapter for optically couplingtwo optical fiber connectors, each optical fiber connector having anoptical ferrule with a mating end for mating with the mating end of theoptical ferrule of the other connector, and the adapter comprising: ahousing having a first end, a second end opposite the first end, anddefining an axial cavity extending from the first end to the second end,each of the first end and the second end being configured for receivingand selectively retaining one of the optical fiber connectors thereinfor mating of the mating ends of the optical ferrules at a matinglocation within the housing, and the housing comprising: a wall portiondisposed at the mating location and orthogonal to the axial cavity, thewall portion comprising an opening therein for the axial cavity and aperimetrical surface defining the opening, the opening having across-sectional configuration for unhindered passage of the mating endsof the optical ferrules therethrough, and the wall portion, at leastadjacent the opening, having a wall thickness sufficient for engagementof the mating ends of the optical ferrules with the perimetrical openingupon displacement of the mating ends in any direction orthogonal to theaxial direction to limit lateral movement of the mating ends andsubstantially maintain an optical coupling between the mating ends.